libfido2-util: Disable pre-flight checks for credentials with UV

libfido2-util: Disable pre-flight checks for credentials with UV

According to the FIDO2 spec, tokens may not support pre-flight checks
for credentials requiring UV, at least not without at least
`pinUvAuthParam` or `uv = true`. Originally, in #25268, this was
handled by passing a PIN to satisfy `pinUvAuthParams`, but this is not
ideal, since `pinUvAuthParam` can be obtained from either a PIN
or a UV verification. Forcing the user to enter the PIN here (which is
often just the fallback option on UV devices) is no better than just
trying out each device with the actual assertion request.

As a result, this commit disables pre-flight checks when the credential
requires UV, and instead reverts to the old behavior (trying out each
device and each key slot, requiring multiple user interactions) for this
type of credentials.